Nuclear Theory·nucl-th

Tuesday·September 1, 2015

19 papers—11 primary·8 cross-listed

01
[Submitted on 28 Aug 2015]
The impact of individual nuclear properties on $r$ -process nucleosynthesis
M. R. Mumpower🇺🇸 · R. Surman🇺🇸 · G. C. McLaughlin🇺🇸 · A. Aprahamian🇺🇸
The astrophysical rapid neutron capture process or ` $r$ process' of nucleosynthesis is believed to be responsible for the production of approximately half the heavy element abundances found in nature. This multifaceted problem remains one of the greatest open challenges in all of physics. Knowledge of nuclear physics properties such as masses, $β$ -decay and neutron capture rates, as well as $β$ -delayed neutron emission probabilities are critical inputs that go into calculations of $r$ -process nucleosynthesis. While properties of nuclei near stability have been established, much still remains unknown regarding neutron-rich nuclei far from stability that may participate in the $r$ process. Sensitivity studies gauge the astrophysical response of a change in nuclear physics input(s) which allows for the isolation of the most important nuclear properties that shape the final abundances observed in nature. This review summarizes the extent of recent sensitivity studies and highlights how these studies play a key role in facilitating new insight into the $r$ process. The development of these tools promotes a focused effort for state-of-the-art measurements, motivates construction of new facilities and will ultimately move the community towards addressing the grand challenge of `How were the elements from iron to uranium made?'.
Comments:
60 pages, 20 figures, review article
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
1508.07352 [pdf]
PPNP(2016)·478 citations
02
[Submitted on 28 Aug 2015]
Electromagnetic structure of light nuclei
Saori Pastore🇺🇸
The present understanding of nuclear electromagnetic properties including electromagnetic moments, form factors and transitions in nuclei with A $\leq$ 10 is reviewed. Emphasis is on calculations based on nuclear Hamiltonians that include two- and three-nucleon realistic potentials, along with one- and two-body electromagnetic currents derived from a chiral effective field theory with pions and nucleons.
Comments:
Invited talk at the 21st International Conference on Few-body Problems in Physics, Chicago, IL, USA, May 18-22, 2015. 9 pages
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1508.07363 [pdf]
EPJ Web Conf.(2016)·2 citations
03
[Submitted on 29 Aug 2015]
Universal noise and Efimov physics
Amy N. Nicholson🇺🇸
Probability distributions for correlation functions of particles interacting via random-valued fields are discussed as a novel tool for determining the spectrum of a theory. In particular, this method is used to determine the energies of universal N-body clusters tied to Efimov trimers, for even N, by investigating the distribution of a correlation function of two particles at unitarity. Using numerical evidence that this distribution is log-normal, an analytical prediction for the N-dependence of the N-body binding energies is made.
Comments:
6 pages, 3 figures. Invited contribution to the 21st International Conference on Few-Body Problems in Physics (FB21)
Subjects:
Nuclear Theory (nucl-th); Quantum Gases (cond-mat.quant-gas); High Energy Physics — Lattice (hep-lat)
arXiv:
1508.07493 [pdf]
EPJ Web Conf.(2016)·1 citation
04
[Submitted on 30 Aug 2015]
The No-Core Gamow Shell Model: Including the continuum in the NCSM
B. R. Barrett🇺🇸 · G. Papadimitriou · N. Michel🇫🇷 · M. Płoszajczak🇫🇷
We are witnessing an era of intense experimental efforts that will provide information about the properties of nuclei far from the line of stability, regarding resonant and scattering states as well as (weakly) bound states. This talk describes our formalism for including these necessary ingredients into the No-Core Shell Model by using the Gamow Shell Model approach. Applications of this new approach, known as the No-Core Gamow Shell Model, both to benchmark cases as well as to unstable nuclei will be given.
Comments:
8 pages, 2 figures, 1 table. Proceedings of the "14th International Conference on Nuclear Reaction Mechanisms", Varenna (Italy), June 15-19, 2015
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1508.07529 [pdf]
4 citations
05
[Submitted on 30 Aug 2015]
Asymptotic normalization coefficients of resonant and bound states from the phase shifts for $α α$ and $α^{12} C$ scattering
Yu.V. Orlov · B.F. Irgaziev · L.I. Nikitina
Recently we have published a paper [Irgaziev, Phys. Rev. C 91, 024002 (2015)] where the $S$ -matrix pole method (SMP) which is only valid for resonances has been developed to derive a new explicit expression for the asymptotic normalization coefficient (ANC), and is applied to the low-energy resonant states of nucleon $+ α$ and $α +^{12} C$ systems. The SMP results are compared with the effective-range expansion method (EFE) results. In the present paper the SMP and EFE plus the Padé-approximation are applied to study the excited 2 $^{+}$ resonant states of $^{8} Be$ . A contradiction is found between descriptions of the experimental phase shift data for $α α$ scattering and of the $^{8} Be$ resonant energy for 2 $^{+}$ state. Using the EFE method, we also calculate the ANC for the $^{8} Be$ ground 0 $^{+}$ state with a very small width. This ANC agrees well with the value calculated using the known analytical expression for narrow resonances. In addition, for the $α +^{12} C$ states1 $^{-}$ and 3 $^{-}$ the SMP results are compared with the Padé-approximation results. We find that the Padé-approximation improves a resonance width description compared with the EFE results. The EFE method is also used to calculate the ANCs for the bound $^{16} O$ ground 0 $^{+}$ state and for the excited 1 $^{-}$ and 2 $^{+}$ levels which are situated near the threshold of $α +^{12} C$ channel.
Comments:
9 pages, 3 figures, 1 table
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1508.07538 [pdf]
PRC(2016)·24 citations
06
[Submitted on 30 Aug 2015]
Benchmark for a quasi-bound state of the $K_pp$ system
Roman Ya. Kezerashvili🇺🇸 · Shalva M. Tsiklauri🇺🇸 · Igor N. Filikhin🇺🇸 · Vladimir M. Suslov🇺🇸 · Branislav Vlahovic
We present three-body nonrelativistic calculations within the framework of a potential model for the kaonic cluster $K^{-} pp$ using two completely different methods: the method of hyperspherical harmonics in the momentum representation and the method of Faddeev equations in configuration space. To perform a numerical benchmark, different $N N$ and antikaon-nucleon interactions are applied. The results of the calculations for the ground state energy for the $K^{-} pp$ system obtained by both methods are in reasonable agreement. Although the ground state energy is not sensitive to the $N N$ interaction, it shows very strong dependence on the $K_N$ potential. We show that the dominant clustering of the $K^{-} pp$ system in the configuration $Λ (1405) + p$ allows us to calculate the binding energy to good accuracy within a simple cluster approach for the differential Faddeev equations. The theoretical discrepancies in the binding energy and width for the $K^{-} pp$ system related to the different $N N$ and $K_N$ interactions are addressed.
Comments:
14 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1508.07638 [pdf]
2 citations
07
[Submitted on 31 Aug 2015]
A possible framework of the Lipkin model obeying the su(n)-algebra in arbitrary fermion number. I --- The su(2)-algebras extended from the conventional fermion-pair and determination of the minimum weight states ---
Yasuhiko Tsue (Kochi Univ., Japan) · Constanca Providencia (Univ. de Coimbra, Portugal) · Joao da Providencia (Univ. de Coimbra, Portugal) · Masatoshi Yamamura (Kansai Univ., Japan)
The minimum weight states of the Lipkin model consisting of n single-particle levels and obeying the su(n)-algebra are investigated systematically. The basic idea is to use the su(2)-algebra which is independent of the su(n)-algebra. This idea has been already presented by the present authors in the case of the conventional Lipkin model consisting of two single-particle levels and obeying the su(2)-algebra. If following this idea, the minimum weight states are determined for any fermion number occupying appropriately n single-particle levels. Naturally, the conventional minimum weight state is included: all fermions occupy energetically the lowest single-particle level in the absence of interaction. The cases n=2, 3, 4 and 5 are discussed in rather detail.
Comments:
28 pages, 6 figurs
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1508.07672 [pdf]
PTEP(2016)·2 citations
08
[Submitted on 31 Aug 2015]
Construction of KbarN potential and structure of Lambda(1405) based on chiral unitary approach
Kenta Miyahara🇯🇵 · Tetsuo Hyodo🇯🇵
Based on chiral unitary approach, we construct the realistic KbarN local potential, which is useful for the quantitative calculation of Kbar-nuclei. Since the resonance pole structure of the KbarN system seems important for the Kbar-nuclei and the spacial structure of Lambda(1405), we establish the construction procedure of the local potential paying attention to the scattering amplitude in the complex energy plane. Furthermore, for the quantitative study of the Kbar-nuclei, we consider the constraint from the recent experimental data measured by SIDDHARTA, which significantly reduces the uncertainty of the KbarN amplitude. With this new local potential, we estimate the spacial structure of Lambda(1405) and obtain the result indicating the meson-baryon molecular state of Lambda(1405).
Comments:
5 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1508.07707 [pdf]
JPS Conf.Proc.(2016)·5 citations
09
[Submitted on 31 Aug 2015]
Possibility of DCC formation in pp collisions at LHC energy via reaction-diffusion equation
Partha Bagchi🇮🇳 · Arpan Das🇮🇳 · Srikumar Sengupta🇮🇳 · Ajit M. Srivastava🇮🇳
There are indications of formation of a thermalized medium in high multiplicity pp collisions at LHC energy. It is possible that such a medium may reach high enough energy density/temperature so that a transient stage of quark-gluon plasma, where chiral symmetry is restored, may be achieved. Due to rapid 3-dimensional expansion, the system will quickly cool undergoing spontaneous chiral symmetry breaking transition. We study the dynamics of chiral field, after the symmetry breaking transition, for such an event using reaction-diffusion equation approach which we have recently applied for studying QCD transitions in relativistic heavy-ion collisions. We show that the interior of such a rapidly expanding system is likely to lead to the formation of a single large domain of disoriented chiral condensate (DCC) which has been a subject of intensive search in earlier experiments. We argue that large multiplicity pp collisions naturally give rise to required boundary conditions for the existence of slowly propagating front solutions of reaction-diffusion equation with resulting dynamics of chiral field leading to the formation of a large DCC domain.
Comments:
17 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1508.07752 [pdf]
PRC(2016)·1 citation
10
[Submitted on 31 Aug 2015]
Single Freeze-Out, Statistics and Pion, Kaon and Proton Production in Central Pb-Pb Collisions at $s_{N N} = 2.76$ TeV
Dariusz Prorok🇵🇱
Many data in the high energy physics are, in fact, sample means. It is shown that when this exact meaning of the data is taken into account and the most weakly bound states are removed from the hadron resonance gas, the acceptable fit to the whole spectra of pions, kaons and protons measured at midrapidity in central Pb-Pb collisions at $s_{N N} = 2.76$ TeV [Phys.Rev.Lett.109,252301(2012)] is obtained. The invariant distributions are predicted with the help of the single-freeze-out model in the chemical equilibrium framework. Low $p_{T}$ pions and protons are reproduced simultaneously as well as $p / π$ ratio. Additionally, correct predictions extend over lower parts of large $p_{T}$ data. Some more general, possible implications of this approach are pointed out.
Comments:
10 pages, 2 figures, matches published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1508.07922 [pdf]
J.Phys.G(2016)·12 citations
11
[Submitted on 31 Aug 2015]
Evaluation of the forward Compton scattering off protons: I. Spin-independent amplitude
Oleksii Gryniuk🇩🇪 · Franziska Hagelstein🇩🇪 · Vladimir Pascalutsa (JGU Mainz)🇩🇪
We evaluate the forward Compton scattering off the proton, based on Kramers-Kronig kind of relations which express the Compton amplitudes in terms of integrals of total photoabsorption cross sections. We obtain two distinct fits to the world data on the unpolarized total photoabsorption cross section, and evaluate the various spin-independent sum rules using these fits. For the sum of proton electric and magnetic dipole polarizabilities, governed by the Baldin sum rule, we obtain the following average (between the two fits): $α_{E 1} + β_{M 1} = 14.0 (2) \times 1 0^{- 4} fm^{3}$ . An analogous sum rule involving the quadrupole polarizabilities of the proton is evaluated too. The spin-independent forward amplitude of proton Compton scattering is evaluated in a broad energy range. The results are compared with previous evaluations and the only experimental data point for this amplitude (at 2.2 GeV). We remark on sum rules for the elastic component of polarizabilities.
Comments:
8 pages, 6 figures, 5 tables
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1508.07952 [pdf]
PRD(2015)·39 citations

Affiliations

first authorsco-authorsvia INSPIRE